The conformation of α，α-disubstituted Cyclododecanones have been studied by means of molecular dynamics computations, 1H NMR and X-ray diffraction analysis. The results indicate that their preferred conformation of ring skeleton is still [3333], with the carbonyl group present in the 2-C position. Both in the crystal and solution, the preferred conformation of α, α-disubstituted Cyclododecanones is α- corner- syn-, α-corner-oraft-disubstituted [3333]-2-one conformation. The first substituted group presents at α -corner- and position, while the second group is at α -corner- syn position.

Key words: cyclododecanone P, CONFORMATION, 1HNMR, XRD, MOLECULAR MECHANICS